<template>
  <div class="spec-preview" @mousemove="mousemove">
    <img :src="skuImageList[imgIndex]?.imgUrl" />
    <div class="event"></div>
    <div class="big">
      <img ref="bigEle" :src="skuImageList[imgIndex]?.imgUrl" />
    </div>
    <div class="mask" ref="maskEle"></div>
  </div>
</template>

<script>
export default {
  name: "Zoom",
  props: ["skuImageList"],
  data() {
    return {
      imgIndex: 0,
    };
  },
  mounted() {
    this.$bus.$on("getZoomIndex", (index) => {
      this.imgIndex = index;
    });
  },
  methods: {
    //放大镜事件函数
    mousemove(e) {
      //得到鼠标到外层元素边缘的距离
      const mouseOut = { x: e.offsetX, y: e.offsetY };
      //计算蒙版的位置
      const maskLoaction = {
        x: mouseOut.x - this.$refs.maskEle.offsetWidth / 2,
        y: mouseOut.y - this.$refs.maskEle.offsetHeight / 2,
      };
      //临界值的判断
      if (maskLoaction.x < 0) {
        maskLoaction.x = 0;
      } else if (
        maskLoaction.x >=
        e.target.clientWidth - this.$refs.maskEle.offsetWidth
      ) {
        maskLoaction.x = e.target.clientWidth - this.$refs.maskEle.offsetWidth;
      }
      if (maskLoaction.y < 0) {
        maskLoaction.y = 0;
      } else if (
        maskLoaction.y >=
        e.target.clientHeight - this.$refs.maskEle.offsetHeight
      ) {
        maskLoaction.y =
          e.target.clientHeight - this.$refs.maskEle.offsetHeight;
      }
      //赋值给蒙版
      this.$refs.maskEle.style.top = maskLoaction.y + "px";
      this.$refs.maskEle.style.left = maskLoaction.x + "px";

      //大图的赋值
      this.$refs.bigEle.style.top = -2 * maskLoaction.y + "px";
      this.$refs.bigEle.style.left = -2 * maskLoaction.x + "px";
    },
  },
};
</script>

<style lang="less">
.spec-preview {
  position: relative;
  width: 400px;
  height: 400px;
  border: 1px solid #ccc;

  img {
    width: 100%;
    height: 100%;
  }

  .event {
    width: 100%;
    height: 100%;
    position: absolute;
    top: 0;
    left: 0;
    z-index: 998;
  }

  .mask {
    width: 50%;
    height: 50%;
    background-color: rgba(0, 255, 0, 0.3);
    position: absolute;
    left: 0;
    top: 0;
    display: none;
  }

  .big {
    width: 100%;
    height: 100%;
    position: absolute;
    top: -1px;
    left: 100%;
    border: 1px solid #aaa;
    overflow: hidden;
    z-index: 998;
    display: none;
    background: white;

    img {
      width: 200%;
      max-width: 200%;
      height: 200%;
      position: absolute;
      left: 0;
      top: 0;
    }
  }

  .event:hover ~ .mask,
  .event:hover ~ .big {
    display: block;
  }
}
</style>
